Water Pump Impeller Kit – Fits Yamaha F40/F70 4-Stroke 2010-2016 (Replaces 6CJ-W0078-00, 6CJ-W0078-01)

Water Pump Impeller Kit – Fits Yamaha F40/F70 4-Stroke 2010-2016

This complete water pump impeller service kit is designed for Yamaha 4-Stroke outboard models, specifically the F40 (6CY) from 2011–2016 and the F70 (6CJ) from 2010–2016. It includes all necessary components to service and rebuild the lower unit water pump assembly, ensuring optimal engine cooling.

This kit is a direct replacement for Yamaha OEM part numbers 6CJ-W0078-00-00 and 6CJ-W0078-01-00. It also cross-references with Sierra 18-3494 and Forestity 6CJ-W0078-00.

• Includes a high-performance neoprene impeller, gaskets, plates, and seals for a complete overhaul.
• Designed for installation in the lower unit/gearcase.
• Built to meet or exceed OEM specifications for reliable performance.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Yamaha owners, here’s a guide to help you identify your engine’s serial/model: Yamaha Serial Number Guide. You can also review exploded diagrams to verify part numbers: Yamaha Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This comprehensive kit includes the following components:

• 1 x Insert, Cartridge (63D-44322-00-00)
• 1 x Gasket, Water Pump (6CJ-44315-00-00)
• 1 x Cover, Pump Housing (63D-44312-00-00)
• 1 x Damper, Water Seal 2 (Replaces 663-44366-00-00 / 663-44366-01-00)
• 1 x Impeller (6H3-44352-00-00)
• 1 x Key, Woodruff (90280-03M03-00)
• 2 x Oil Seal (93101-23070-00)
• 1 x O-Ring (93210-46044-00)
• 1 x Gasket, Water Pump (6CJ-44316-00-00)
• 1 x Outer Plate, Cartridge (6CJ-44323-00-00)
• 1 x Gasket, Cartridge (6CJ-44324-00-00)
• 2 x Pin, Dowel (93604-10M03-00)
• 2 x Bolt, With Washer (90119-08M33-00)
• 2 x Bolt, With Washer (90119-08M14-00)

Explosion Diagram

Installation Guide

1. Disconnect the battery and shift the outboard into neutral.
2. Remove the lower unit (gearcase) bolts and carefully lower the unit from the outboard.
3. Unbolt the 4-bolt water pump housing and slide it up the driveshaft.
4. Clean the mating surfaces and remove the old impeller, key, gaskets, and plates. Note their orientation.
5. Install the new seals, gaskets, and Woodruff key from the kit.
6. Slide the new impeller down the driveshaft and into the housing, rotating the driveshaft clockwise to seat the vanes correctly.
7. Install the new housing, cartridge, and associated components as per the diagram.
8. Torque all bolts to the manufacturer's specifications.
9. Reinstall the lower unit, ensuring the driveshaft, water tube, and shift shaft are correctly aligned.
10. Test the engine on a water supply, confirming a strong, steady stream from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this fits my engine?

This kit is confirmed to fit Yamaha F40 and F70 models from 2010-2016 that use OEM part 6CJ-W0078-01-00. The compatibility table lists specific models like F40 (6CY) and F70 (6CJ). While some sources suggest it may fit F70LA models up to 2021, we recommend verifying your engine serial number and existing part numbers before ordering.

What are the signs my water pump needs replacing?

A weak or no water stream from the engine's tell-tale outlet is the most common sign. Other indicators include the engine overheating alarm activating or finding cracked, stiff, or damaged vanes on the impeller during a visual inspection.

How often should I replace the water pump impeller kit?

For preventative maintenance, it is best practice to replace your water pump impeller and gaskets every 2 to 3 years or every 200-300 hours of operation, especially for boats used in saltwater.

My old part is 6CJ-W0078-00-00. Will this kit work?

Yes. Yamaha officially superseded part number 6CJ-W0078-00-00 to 6CJ-W0078-01-00. This kit is the correct replacement for both OEM part numbers.

OEM vs. Aftermarket?

This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?

We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?

This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.